A small two-cycle internal combustion engine used as a driving source for portable working machines such as a chain saw, a brush cutter and the like is equipped with a diaphragm type carburetor so that excellent operation of the internal combustion engine may be controlled in any attitude.
As disclosed in Japanese patent application Laid-Open Publication No. 35047/1987, there is proposed an arrangement wherein when the engine is started, fuel is supplied from a fuel tank to a metering chamber by a manual primer pump, the fuel being also present in an accumulator chamber, and a button of an accumulator is operated simultaneously with the starting rotation operation (cranking) of the engine to supply the fuel in the accumulator from a fuel nozzle to an air intake passage of a carburetor. However, recently, the internal combustion engine equipped with a battery operated motor has been mounted on the aforementioned portable working machine. It is desirable that a power supply for driving the motor is utilized to automatically perform a series of operations.
It is an object of the present invention to provide an apparatus for supplying start-fuel in the internal combustion engine for a portable type working machine in which replenishment of fuel to a metering chamber and supplying of start-fuel to a fuel nozzle are automatically effected by normal and reverse rotations of a primer pump driven by an electric motor.